Number of permutations that are sortable with two stacks in series.

A263929

Number of permutations that are sortable with two stacks in series.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =120a(6) =720a(7) =5018a(8) =39374a(9) =337816a(10) =3092691a(11) =29659731a(12) =294107811a(13) =2988678546a(14) =30935695794a(15) =324832481490

External references